Electronic oscillator



Feb. 14, 1939. 3 MORTON 2,147,454

ELECTRONIC OSCILLATOR Filed Dec. 24, 1936 7'0 L OHD OR QU'I'PU'I' CIRCUIT Snnentor George H. Morton B 7 Gttorneg Patented Feb. 14, 1939 UNITED. STATES V 2.147.454 nnncrnomc oscmm'ron George A. Morton, Audubon, N. J., assignor to Radio Corporation oi America, a corporation of Delaware Application December 24, 1936, Serial No. 117,669

5 Claims.

My invention relatesto electronic oscillators, and more particularly to a high frequency oscillator in which the transient time of electrons is a function of the frequency of the oscillator.

I am aware that various types of electronic oscillators have been employed in which the frequency of the oscillations is a function of the transient time of the electrons moving between the cathode and one or more additional electrodes within the electronic tube. I propose to provide means for substantially increasing the efiiciency of electronic oscillators by subtracting energy from the moving electrons in several successive steps until the velocity of the moving electrons becomes very low.

The principal object of my invention is to provide means for establishing electronic oscillations in a resonant circuit.

Another object of my invention is to provide means for successively subtracting energy from a-mass of moving electrons as their velocity is gradually reduced by an energy absorbing circuit.

A still furtherobject of my invention is to provide means for successively changing the phase of the potentials applied to a plurality of electrodes, arranged along the path of the moving electrons in a thermionic tube, as a function of the moving electrons.

My invention may be best understood by reference to the accompanying drawing, in which a thermionic tube I is arranged as follows: Within an evacuated envelope 3, a cathode 5, a grid I, an accelerating anode 9, a plurality of electrodes II, I3, I5, I1, I9 and a target 2| are arranged. These electrodes, II, I3, etc., are hollow cylinders of successively smaller lengths concentrically arranged along a common axis. The cathode, grid, accelerating anode and target are electrodes of the conventional shape, which are likewise concentrically arranged along the common axis. A suitable magnetic field may be supplied by an electromagnet 23, a permanent magnet, solenoid, or the like.

A resonant circuit 25, composed of a center tapped inductor. 21 and a variable capacitor 29, is connected so that one of the circuit terminals 3| is connected to alternate electrodes II, I5 and I9. The other circuit terminal 33 is connected to electrodes I 3 and II, which are respectively positioned intermediate electrodes II, I5 and intermediate electrodes I5, I9. A biasing battery 35 is connected between the cathode 5 and the accelerating anode 9. The cente'rtap of the resonant circuit 25 is also connected to the battery 35. A second battery, or a suitable'tap on the first mentioned battery 35, is used to bias the target 2| positively with respect to the cathode 5. The unipotential cathode 5 is energized by a heater 31, which is connected to a battery 39 or the like.

Although not essential, I have found that a 5 resonant circuit 4 I, comprising an inductor 43 and a variable capacitor 45, may be connected. be: tween the cathode 5 and the grid 1, and mutually coupled to -the resonant circuit 25. The second resonant circuit 4|, if properly phased with respect to the first resonant'circuit 25, greatly increases the efiiciency of the oscillator.

The operation of the foregoing device is as follows: Electrons emitted from the cathode! leave the cathode at yery high velocities under the influence of the accelerating anode 9. A transitory current is established in the resonant circuit 25. It is assumed that the terminal 3|, connected to the electrode II, is at a negative potential at the instant when the highly accelerated electrons are entering the electrode II. The electrons thus entering the field of the electrode II are opposed in their motion by the potential of the electrode I I, and thus energy is subtracted from the moving electrons and delivered to the resonant circuit.

As the electrons proceed, they are moving at slower velocities, due to the subtraction of energy, and are about to enter the field of the electrode I3 just as the potential applied to this electrode is made negative, upon reversal of the current in the resonant circuit 25. Thus the electrons which are now moving at slower velocities are again opposed by the influence of the negative field within the electrode I3. These electrons deliver energy to electrode I3 and to the oscillating circuit 25.

The current in the resonant circuit again reverses its phasein timeto oppose the electrons leaving the field of electrode I3 and entering the field of electrode I5. At this point, the electrons are moving at still slower velocities, and have delivered more energy to the resonant circuit. Their motion is again opposed and, by this opposition, more energy is subtracted from the moving electrons. This energy is also delivered to the oscillating circuit. This process may be continued along the path which the electrons are following, until substantially all of their energy is subtracted, at which time the electrons reach the target 2|. 50

In order that the electrons leaving the cathode .and accelerated by the anode 9 may reach the first of the electrodes connected to the resonant circuit 25 in the proper phase, I prefer to couple the resonant circuit 3 I which has been hereinbe- 55 fore described, to the resonant circuit 25. If the circuits are suitably phased, the grid 1 will ad- Vance or retard the electrons to thereby properly phase their entry into the field on the electrode I I. While this latter connection makes it possible to correctly phase the electrons, I have found that this connection is not essential and may be omitted in devices where lower operating efiiciencies may sufllce.

Likewise, it should be understood that the ma netic field, which tends to focus the electrons, is not essential, as the electrons themselves are able to form a beam which traverses the common axis of the various electrodes.

The several electrodes H, B, etc., are each successively shorter and may be biased by the same or difierent voltages. The transient time, that is, the time required for the electrons to pass through the several electrodes, is determined by the length of the successive electrodes, the velocity at which the electrons enter the respective electrodes, and their respective potentials. It will be apparent that the resonant period of the resonant circuit 25 should equal the period required for the electrons to travel the distances between the successive electrodes.

I claim as my invention:

1. An electronic oscillator including, in combination, an emissive electrode, an accelerating electrode, a target electrode and a plurality of electrodes arranged along a common axis between said accelerating electrode and said target, a resonant circuit having its terminals connected to alternate ones of said plurality of electrodes, and means for biasing said accelerating electrode, said target electrode, and said plurality of electrodes positively with respect to said emissive electrode, whereby energy may be successively subtracted by said resonant circuit as electrons pass from said emissive electrode to said target electrode.

2. An electronic oscillator including, in combination, a cathode, control grid, accelerating electrode, target electrode, and a plurality of electrodes arranged along a common axis between said accelerating electrode and said target, a resonant circuit having its terminals connected to alternate ones 01 said plurality of electrodes, means for biasing said accelerating electrode, said target electrode, and said plurality of electrodes positively with respect to mid cathode, and means connected to said control grid for controlling the phases of electrons approaching said plurality of electrodes.

phases of electrons approaching said plurality of electrodes.

4. An electronic oscillator including, in combination, a thermionic tube including an emissive electrode, a control electrode, a target electrode, and a plurality of electrodes arranged between said emissive electrode and target, a resonant circuit having its terminals connected to alternate ones of said plurality of electrodes, means for biasing said accelerating electrode, said target electrode, and said plurality of electrodes positively with respect to said emissive electrode, a second resonant circuit coupled to said first-mentioned resonant circuit and effectively connected'between said control electrode and said emission electrode whereby electrons emitted from said emissive'electrode may be phased with respect to the instantaneous potential of the first of said plurality of electrodes.

5. An electronic oscillator including, in combination, a thermionic tube including an -emissive electrode, a control electrode, a target electrode, and a plurality of electrodes of successively shorter lengths arranged between said emissive electrode and target, a resonant circuit having its terminals connected to alternate ones of said plurality of electrodes, means for biasing said accelerating electrode, said target electrode, and said plurality of electrodes positively with respect to said emissive electrode, a second resonant circuit coupled to said first-mentioned resonant circuit and eflfectively connected between said control electrode and said emissive electrode whereby electrons emitted from said emissive electrode may be-phased with respect to the instantaneous potential of the first of said plurality of electrodes whereby energy may be successively subtracted from electrons moving past said plurality of electrodes by said plurality of electrodes and said first-mentioned resonant circuit.

GEORGE. A. MORTON. 

